ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus PublicationsGöttingen, Germany10.5194/acp-5-2761-2005Observation of 2-methyltetrols and related photo-oxidation products of isoprene in boreal forest aerosols from Hyyti&#228;l&#228;, FinlandKourtchevI.1RuuskanenT.2MaenhautW.3KulmalaM.2ClaeysM.11Department of Pharmaceutical Sciences, University of Antwerp (Campus Drie Eiken), Universiteitsplein 1, 2610 Antwerp, Belgium2Department of Physical Sciences, Division of Atmospheric Sciences, University of Helsinki, P.O. Box 64, Gustaf Hällstrminkatu 2, 00 014 Helsinki, Finland3Department of Analytical Chemistry, Institute for Nuclear Sciences, Ghent University, Proeftuinstraat 86, 9000 Gent, Belgium2110200551027612770This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article is available from http://www.atmos-chem-phys.net/5/2761/2005/acp-5-2761-2005.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/2761/2005/acp-5-2761-2005.pdf

Oxidation products of isoprene including 2-methyltetrols (2-methylthreitol
and 2-methylerythritol), 2-methylglyceric acid and triol derivatives of
isoprene (2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and
3-methyl-2,3,4-trihydroxy-1-butene) have been detected in boreal forest
PM<sub>1</sub> aerosols collected at Hyyti&#228;l&#228;, southern Finland, during a
2004 summer period, at significant atmospheric concentrations (in total 51 ng m<sup>&minus;3</sup>
in summer versus 0.46 ng m<sup>&minus;3</sup> in fall). On the basis of
these results, it can be concluded that photo-oxidation of isoprene is an
important atmospheric chemistry process that contributes to secondary
organic aerosol formation during summer in this conifer forest ecosystem. In
addition to isoprene oxidation products, malic acid, which can be regarded
as an intermediate in the oxidation of unsaturated fatty acids, was also
detected at high concentrations during the summer period (46 ng m<sup>&minus;3</sup> in
summer versus 5.2 ng m<sup>&minus;3</sup> in fall), while levoglucosan, originating from
biomass burning, became relatively more important during the fall period
(29 ng m<sup>&minus;3</sup> in fall versus 10 ng m<sup>&minus;3</sup> in summer). Pinic acid, a major
photo-oxidation product of &alpha;-pinene in laboratory experiments, could
only be detected at trace levels in the summer samples, suggesting that
further oxidation of pinic acid occurs and/or that different oxidation
pathways are followed. We hypothesize that photo-oxidation of isoprene may
participate in the early stages of new particle formation, a phenomenon
which has been well documented in the boreal forest environment.